most everything needs water to survive, so I would look for water first. If you can't find water, make a place for water to gather. I once seen a show where a guy dug a ditch in a desert, laid a tarp in the ditch, poked a hole in the middle of the tarp, and put a can under the hole. After morning, the dew gathered and ran down the tarp into the can. It was enough to get a good drink from. Granted you need these supplies, but I bet you could compensate.

What about warmth?...I haven't tried this yet, but it sounds clever. After you establish your fire, gather rocks. Put the rocks in the fire to heat up. Dig a small ditch about 4-8 inches deep (enough to cover said rocks) and as long as you are. Put the rocks in after they are HOT. Cover with earth from the digging, and set your sleeping bag over the trench. The earth will insulate the rocks and keep the heat in. No sleeping bag?, gather leaves and test temp. so you don't burn your ass

I too have eaten fresh water messels, and crawdads. Both were terrible! I am sure that both would taste much better with a little more effort than I gave it, and a "survival appetite". Dandelion greens seem good to me, but I always drain the first boil water, then add new water and bring to a simmer. It seems to rid most of the bitterness, and some salt&pepper helps out, too.

can some deer meat, i have some that's 6 years old and still tastes good. you can can anything almost, even bread.

if the SHTF, don't count on there being too many large sized animals left around for long. A buddy of mine, his dad grew up during the depression. He said the first year wasn't such a big deal becuase everyone hunted. he said the second year there wasn't a deer or squirrel left....